Scarring pattern of whale sharks (Rhincodon typus) and its implications for conservation in Bahía de la Paz, Gulf of California, Mexico.
Supervisor: Darren A. Whitehead (Pelagios Kakunja)
Very little is known about the whale shark biology and ecology, although these animals are known to aggregate in identified tropical and subtropical areas of the world, probably for feeding. It is also common knowledge that the species faces many threats, including pollution, targeted and non-targeted fisheries pressure, and boat strikes. To limit the latter, effective and adaptative management strategies are necessary to conserve the species, both locally and globally. In the bay of La Paz (LAP), Mexico, juvenile whale sharks aggregate seasonally along the coast of the El Mogote Sandbar. This relatively small population dominated by males is subject to a growing tourism industry, with a high economic value. Although in the last decade, researchers on site have observed many injuries on the animals, questioning the need to improve the species conservation in this important aggregation site. However, no published literature is available concerning this scarring pattern, and thus, the present study provides a baseline for future scarring studies on the whale sharks in LAP.

Using photo-identification, scar observation, and classification, we observed that, during a complete whale shark season from September 2021 to June 2022, more than 90% of the identified sharks in the area presented injuries. However, slightly less than 30% of these injuries were inflicted during this season, and thus presumably in the area. The main injury types encountered were abrasions, lacerations, and nicks, most frequently on the emerged body parts: the first dorsal fin and the caudal fin. A large majority of these injuries can be attributed to anthropogenic causes and specifically vessel collisions. No relation between the size of the animals and their number of scars was found, as well as no significant difference in the number of fresh scars between sample months. In LAP, many regulations were implemented in the last years, along with a protected refuge area. Still, our results highlight the need for reinforced control and compliance with the rules currently in place. Intensifying public education and outreach initiatives can also benefit whale shark conservation in La Paz.